German Offenlegungsschriften Nos. 2,032,433; 2,308,584; 2,445,791; 2,537,765, and 2,637,162, which are incorporated by reference herein, disclose liquid atomizing devices which produce inhalable aerosols from drug-containing solutions. In these known devices the oscillations of a piezoelectric oscillator are transferred to an atomizer plate that divides the drug-containing solution supplied to it into fine droplets which, together with the air, form an aerosol.
When inhalation aerosol sprays are used for the treatment of bronchial spasms, such as asthma, it is important that a sufficient portion of the aerosol droplets are small enough to be transported with the inhaled air into lungs. If the droplets are too large, they settle out in the mouth or in the upper respiratory passages, so that the desired effect is not achieved at all or only to an insufficient degree. The known inhalation spray devices above referred to have the disadvantage that the aerosols which they produce contain too large a portion of relatively bid droplets that do not reach the lungs.